This invention relates to a method of limiting shifting movement of a winning tool that is mounted on a universally-pivoted tool or support arm of a tunneling machine in a manner to form a tunnel with a desired tunnel cross section. More particularly, the present invention relates to a method and control system for determining the position of the winning tool in relation to a laser beam that projects along the length of the tunnel and for limiting the range of movement by the winning tool according to a set of tool coordinates formed by scanning a pattern, template or the like which defines a geometrically similar outline to the required tunnel cross section. The geometrically similar outline is scanned by a tracing probe, a light-reflective barrier or the like.
It is known in the art to provide a system to control and correct the movements of a tunneling machine or a winning machine which has a cutting tool that is mounted on a movable swing arm. The system includes a control screen located at a driver control station. The control screen has cross-hairs and scales which extend in the direction of the coordinates. The course of travel by the machine is indicated by the impingement of a guide beam on the screen. The control station for the machine also includes a device having a stationary guide frame and a picture frame which is movable relative to the guide frame in the two coordinate directions and includes scales and guides. The picture frame carries a transparent disc and an associated pattern, template or the like which define the required tunnel cross section by a small scale production. The disc and pattern are pivoted together relative to the picture frame and angularly adjustable by means of a device such as a click stop which has a scale calibrated in angles. The guides of the guide frame are employed to guide two crossed pointers which extend in the directions of the two coordinates. The guides are connected by means of known mechanical or hydraulic control elements to either the cutting tool itself or to the swing arm carrying the cutting tool. The same scale dimensions are used on the screen, the pattern and the picture frame. The purpose of these facilities is to enable the machine operator to detect the position and shape of the required tunnel profile. In the event of deviations to the correct movement of the machine and/or tool, such deviations are corrected in a continuous manner without maneuvering the machine to and fro to bring about the correction.
Other forms of tunneling machines known in the art have a winning tool carried on a universally-pivotal arm that has a limited range of operation which corresponds to the required cross section of the tunnel. Tunneling machines of this type employ a pattern, template or the like that defines a shape which is similar to the required tunnel cross section. However, in these instances, the pattern or the like limits the range of operation by the tool so that it corresponds to the required tunnel outline. However, it is impossible for the machine operator to controllably move the tool beyond the tunnel outline. The tunnel outline on the pattern is detected by an abutment that is adjustable by the machine operator or by a light-reflective barrier which the operator guides along the outline of the pattern. The control elements that position the tool support arm are controlled by a servo control to insure that the tool movement remains in a corresponding agreement with the outline of the tunnel profile as defined by scanning the pattern with the light-reflective barrier or with the position of the abutment. The reference or set-value position of the pattern is determined by the beam from a laser transmitter. In the event of deviations, the pattern is moved by the machine operator. The light detector, when scanning by a light-reflective barrier, cannot produce output signals which would allow the tool to be positioned outside of the outline defined by the pattern. In a similar way, the abutment cannot depart from the outline of the pattern so that it is again impossible to provide output signals which would permit the positioning of the tool outside the outline defined by the pattern. Therefore, in this system, positioning of the winning tool is constrained strictly in accordance with the scanned outline of the pattern corresponding to the required tunnel outline and the tool cannot be moved beyond the limits of this outline which is unlike the first-known control system described previously.
Neither of the prior art systems can detect angular deviations of the machine about its longitudinal axis in relation to the laser beam and therefore such deviations cannot be detected by the machine operator. Moreover, it is impossible to compensate for inclinations of the machine about a horizontal axis that extends transversely of the tunnel length or rotational movement of the machine about a vertical axis. An adjustment to the pattern is ineffective to correct all such deviations. Geodetic aids are, therefore, required to maintain alignment of the machine in a longitudinal direction. In other words, geodetic aids are necessary to maintain the machine parallel with the laser beam while the machine moves along in a longitudinal direction of the tunnel.